STRUCTURAL FEATURE OF THE MAJOR BUT NOT CYTOKINE-INDUCING MOLECULAR-SPECIES OF LIPOTEICHOIC ACID

Previously, lipoteichoic acid (LTA) of Enterococcus hirae was found to exhibit definite cytokine-inducing activity but synthetic specimens w hich share the fundamental structural principles proposed for LTA had no corresponding activity, We also showed recently that several minor components totally less than 5% of the LTA fraction from E. hirae ATCC 9790 possessed the activity, whereas the major component (over 90%) d id not [Suda, Y., Tochio, H., Kawano, K., Takada, H., Yoshida, T., Kot ani, S., and Kusumoto, S. (1995) FEMS Immun. Med. Microbiol. 12, 97-11 2]. In the present study, the structure of the major component of LTA was studied in an attempt to elucidate the reason for the lack of the activity in the synthetic compounds. The major component of the LTA wa s first digested by hydrofluoric acid hydrolysis to cleave phosphodies ter linkages present. The hydrolysis products were separated and chara cterized by means of NMR and RIS. The linkage positions of the origina l phosphodiesters were determined from the NMR spectra of an alkali-tr eated product without hydrofluoric acid degradation. The compound was proved to consist of 1,3-linked poly(glycerophosphate) and a lipid anc hor, Glc(alpha 1-2)Glc(alpha 1-3)acyl(2)Gro, the former being linked t o the B-position of the distal glucose of the latter, The a-position o f the glycerol residues in the glycerophosphate part were substituted by oligoglucose esterified partially with alanine. The gross structure elucidated here thus coincides with the previous conclusion described by Fischer [Fischer, W. (1990) in Glycolipids, Phosphoglycolipids and Sulfoglycolipids (Kates, M., ed.) pp. 123-234, Plenum Press, New York ]. Thus, the molecular species with this so-called ''LTA structure'' i s not responsible for the cytokine-inducing activity.